Perfluoroalkyl and Polyfluoroalkyl Substances (PFASs) in Groundwater at a Reclaimed Water Recharge Facility

Abstract

Reclaimed water is becoming an increasingly important source of water in arid regions worldwide. In the City of Tucson, Arizona, reclaimed water makes up approximately 10% of the annual water supply. It is used for a variety of purposes that include recharging the local aquifer, creating surface flow in the Santa Cruz River, and irrigating parks, golf courses, and other turf irrigation such as recreational fields. Recently, Tucson Water discovered high concentrations of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in their reclaimed water system. High concentrations of PFASs were detected by Tucson Water in the Sweetwater Recharge Facility (SRF), adjacent to the Santa Cruz River, where reclaimed water is stored underground in the alluvial aquifer. PFASs have gained national attention as emerging contaminants because of their toxicological impact to humans and persistence in the environment, yet little is known about their fate and transport. Initial results from this study show that PFASs in the SRF are most probably sourced from the retired wastewater treatment facility. Lower PFASs concentrations have been observed in the treated wastewater provided by the new treatment facility. Moreover, PFAS concentrations were found to be almost directly related to rising and falling groundwater levels, indicating that PFASs could be trapped in the vadose zone and transported to the aquifer during managed aquifer recharge events.